There are many situations in which there is a need to strip the outer insulating cover off an end portion of a wire. Such stripping may be accomplished by hand using a knife, but hand stripping has several serious drawbacks. Hand stripping can be hazardous to the worker doing the stripping and is also very time-consuming. In addition, manual stripping tends to result in nicking and scarring of the wire core. In some environments, such as sophisticated aircraft environments, even slight nicking or scarring of the wire core is unacceptable. Power strippers that speed up the stripping process and reduce the hazards to the worker and the tendency to scar the wire are commercially available. However, such power strippers are generally not portable and are limited to stripping wire smaller than AWG No. 10. Thus, a need exists for a hand held portable power stripper that can handle large gauge wire and that can be used in a variety of environments, including shops, airfields, and areas on board aircraft.
Tools for stripping wires are disclosed in the following U.S. Pats. Nos. 2,054,529, granted Sept. 15, 1936, to E. J. Wiggins; 2,571,078, granted Oct. 9, 1951, to J. Vollmer; 2,724,985, granted Nov. 29, 1955, to R. R. Chamberlin; 3,089,367, granted May 14, 1963, to H. P. Schluter; 3,154,980, granted Nov. 3, 1964, to R. L. Hayden, et al; 3,176,550, granted Apr. 6, 1965, to R. A. Marcotte; 3,222,957, granted Dec. 14, 1965, to L. Kramer, et al; 3,530,746, granted Sept. 29, 1970, to R. Gudmestad; 3,563,117, granted Feb. 16, 1971, to F. P. J. Bolssens; 3,727,492, granted Apr. 17, 1973, to Vincenzo Zanni; 3,765,277, granted Oct. 16, 1973, to William W. Sorensen; 3,880,022, granted Apr. 29, 1975, to Harry E. Miller; 4,072,069, granted Feb. 7, 1978, to Zdzislaw Bieganski; and 4,329,891, granted May 18, 1982, to Zdzislaw Bieganski. West German Pat. No. 2,834,904, granted Mar. 8, 1979, to Hitachi, Ltd., Tokyo, discloses a tool for wrapping wire around studs which apparently includes a wire stripping mechanism.
The Wiggins patent discloses a wire stripper which has pivotably mounted knives and no separate gripper and in which pulling the wire causes the knives to pivot into a closed position to cut and strip the insulation. Marcotte discloses a stripper having pivotably mounted knives that are closed by a piston and toggle link arrangement, and gripping jaws similarly mounted and operated that pull the end of the insulation off the wire and let it drop out of the stripper. Kramer et al. disclose cutters that are pivotably mounted on a slide and are closed by contact with a stop, and pivotably mounted clamping jaws that are activated by a spring loaded toggle mechanism. Bolssens discloses a portable stripper in which a cam on a piston rod allows springs to move one gripping jaw and one cutting jaw laterally to engage the wire and in which the pairs of jaws are moved apart to strip the wire. The portable stripper disclosed in the Zanni patent includes two pairs of jaws, one for clamping and one for cutting, each of which has two jaws that are pivotably connected, biased apart by a spring, and closed by contact with an inclined plane cam surface on a longitudinally movable slide. Sorensen discloses a portable stripper in which cutter jaws and gripper jaws are pivotably mounted and closed by toggle links and in which the cutter jaws are mounted on a slide and moved axially to strip the wire. Miller discloses a portable stripper which has two rigid V-shaped cutting blades, in which wire is cut by being inserted into the V's formed by the blades, and in which the wire is stripped by moving one blade with respect to the other. The first Bieganski patent discloses a portable stripper having pivotably mounted clamping jaws that are closed by a cam surface on a sliding rod that separates a pair of rollers that are pivotably connected to the jaws, and cutting jaws that are pivotably connected to the rod, are pressed together by the pivoting of the clamping jaws, and move longitudinally to strip the wire. The second Bieganski patent discloses a stripper that resembles a pair of pliers and has pivotably mounted gripping jaws which are closed by toggle links and pivotably mounted cutting jaws which are closed by the gripping jaws.
The Vollmer patent discloses apparatus for processing wire that includes a stripping mechanism. The stripping mechanism has clamping fingers for gripping the wire, which fingers are pivotably mounted on gears so that they "will work together". The jaws are moved longitudinally to strip the wire. The knives that cut the insulation are mounted on opposing slides and are moved laterally into contact with the insulation by a rack and pinion mechanism.
Chamberlin discloses a portable wire stripper in which a thumb button is pressed to grip the wire and then a trigger is pulled to engage the knives. The gripping jaws are mechanically linked to the thumb button and move longitudinally when the thumb button is pressed. As the jaws move longitudinally, they are urged together by contact with a tapered inner surface of the housing. The knives are operated by the trigger in a similar manner, being first cammed inwardly to cut the insulation and then pulled longitudinally to strip the wire. The stripper has an adjustable stop for adjusting the amount of insulation stripped. Chamberlin states that the piece of stripped insulation falls out of or "may be discharged from" holes in the stripper.
Schluter discloses a portable device in which insulation is stripped from a wire by "well-known means" and then a metal braid covering is stripped. The mechanism for cutting and stripping the metal braid includes a main cylinder and a piston which reciprocates in the cylinder and which carries resilient gripper fingers and an annular cutting edge. The gripper fingers extend axially and terminate in radially extending ends that grip the braid. When the gripper fingers move axially, they are cammed shut by contact with two pins secured to the housing. Further movement of the gripper fingers causes the braid to bulge, and the axially moving cutter cuts the braid at the bulge. The device has an ejecter pin for ejecting the severed piece of braid, which ejecter pin is actuated by a separate cylinder positioned inside the main cylinder.
In the Hayden et al. portable wire stripper, gripping jaws and separate cutters are moved laterally into contact with the wire. The jaws and the cutters are cam operated by relative movement between stationary pins and longitudinally tapered slots. After the insulation is cut, longitudinal movement of the gripping jaws pulls the wire away from the cutters to strip the severed insulation. The stripper is powered by a single-acting, spring return air cylinder. On the return stroke of the cylinder, air is discharged through a three-way valve and directed to the region of the cutting heads to blow the severed insulation clear of the device.
The Gudmestad patent discloses electrical apparatus for unwinding, cutting, and stripping wire. The apparatus includes gripping jaws for moving the severed wire laterally to a stripping work station. These gripping jaws are pivotably mounted and interconnected by gears so that they will open and close simultaneously. At the stripping station, there are a pair of gripping jaws, one of which is stationary and one of which pivots, and a pair of blades mounted on slides. The pivotable gripper jaw is cam operated, and the blades are connected by toggle levers and cam operated.
The above patents and the prior art that is discussed and/or cited therein should be studied for the purpose of putting the present invention into proper perspective relative to the prior art.